Methods of depositing coatings with γ-Ni + γ′-Ni3A1 phase constitution

Abstract

A method including depositing a powder on a substrate to form a first layer thereon, wherein the layer includes a Pt group metal, Si and reactive element selected from the group consisting of Hf, Y, La, Ce, Zr, and combinations thereof. Deposited on the first layer is a second layer including Al to form a coating with a γ-Ni+−γ′Ni 3 Al phase constitution. In preferred embodiments, the second layer is deposited with an organo halocarbon activator.

1. A method comprising:
 electrophoretically depositing a powder comprising a mixture of a Pt group metal, Si, and a reactive element selected from the group consisting of Hf, Y, La, Ce, Zr, and combinations thereof on a substrate to form a first layer thereon, wherein the first layer comprises the Pt group metal, Si and the reactive element selected from the group consisting of Hf, Y, La, Ce, Zr, and combinations thereof; and 
 depositing on the first layer a second layer comprising Al to form a coating comprising a γ-Ni+γ′-Ni 3 Al phase constitution. 
 
     
     
       2. The method of  claim 1 , wherein the Pt-group metal comprises at least one of Pt, Pd, Ir, Rh and Ru. 
     
     
       3. The method of  claim 1 , wherein the coating further comprises at least one of Cr, Co, Mo, Ta, Ti, W, and Re. 
     
     
       4. The method of  claim 1 , wherein the powder comprises about 84 wt. % to about 93 wt. % Pt, about 3 wt. % to about 12 wt. % Si and about 2 wt. % to about 6 wt. % Hf. 
     
     
       5. The method of  claim 1 , wherein the at least one of the first and second layers are deposited by electrophoresis. 
     
     
       6. The method of  claim 5 , wherein the second layer is deposited from an electrophoretic suspension comprising solids including about 0.5 wt. % to about 25 wt. % of an Al source, about 1 wt. % to about 10 wt. % of an organo halocarbon activator, and a filler. 
     
     
       7. The method of  claim 6 , wherein the Al source comprises at least one of elemental Al, an aluminum-chromium alloy, an organo-aluminum compound, or an aluminum-chromium-manganese alloy. 
     
     
       8. The method of  claim 1 , wherein the second layer is deposited by pack cementation. 
     
     
       9. The method of  claim 8 , wherein the pack comprises about 0.5 wt. % Al to about 5 wt. % Al, about 1 wt. % to about 10 wt. % organo halocarbon activator, less than about 5 wt. % of at least one reactive element comprising Hf, Y, La, Ce, and Zr, and a filler. 
     
     
       10. The method of  claim 1 , wherein the second layer is deposited from a source comprising Al and an organo halocarbon activator. 
     
     
       11. The method of  claim 10 , wherein the organo halocarbon activator comprises polytetrafluoroethylene. 
     
     
       12. The method of  claim 1 , wherein the coating comprises a predominately γ-Ni+γ′-Ni 3 Al phase constitution. 
     
     
       13. The method of  claim 1 , further comprising applying at least one heat treatment following depositing at least one of the first and second layers. 
     
     
       14. The method of  claim 1 , further comprising applying a heat treatment after depositing the first layer. 
     
     
       15. The method of  claim 14 , wherein the first layer comprises up to about 30 at.% of a Pt-group metal, up to about 2 at.% of a reactive element, and up to about 28 at.% Si. 
     
     
       16. The method of  claim 14 , wherein the first layer comprises about 10 at.% to about 30 at.% of a Pt-group metal, about 0.3 at.% to about 2 at.% of a reactive element, and about 2 at.% to about 28 at.% Si. 
     
     
       17. The method of  claim 15 , wherein the first layer comprises up to about 20 at.% Al, up to about 8 at.% Cr, and up to about 8 at.% Co. 
     
     
       18. The method of  claim 16 , wherein the first layer comprises about 10 at.% to about 20 at.% Al, about 2 at.% to about 8 at.% Cr, and about 4 at.% to about 8 at.% Co. 
     
     
       19. A method comprising:
 electrophoretically depositing a powder comprising a substantially homogeneous mixture of a Pt group metal, Si, and a reactive element selected from the group consisting of Hf, Y, La, Ce, Zr, and combinations thereof on a substrate to form a first layer comprising the Pt group metal, Si, and the reactive element; and 
 depositing a second layer comprising Al on the first layer to form an alloy including a γ-Ni+γ′-Ni 3 Al phase constitution, wherein the second layer is deposited with an organo halocarbon activator. 
 
     
     
       20. The method of  claim 19 , wherein the organo halocarbon comprises polytetrafluoroethylene. 
     
     
       21. The method of  claim 19 , wherein the first layer is deposited using electrophoresis. 
     
     
       22. The method of  claim 19 , wherein the second layer is deposited with a pack cementation process. 
     
     
       23. The method of  claim 22 , wherein the pack comprises about 0.5 wt. % Al to about 5 wt. % Al, about 1 wt. % to about 10 wt. % fluorocarbon, less than about 5 wt. % of the reactive element, and a filler. 
     
     
       24. The method of  claim 19 , wherein the second layer is deposited using electrophoresis. 
     
     
       25. The method of  claim 24 , wherein the second layer is deposited from an electrophoretic suspension comprising solids including about 0.5 wt. % to about 25 wt. % of an Al source, about 1 wt. % to about 10 wt. % of an organo halocarbon activator, and a filler. 
     
     
       26. The method of  claim 19 , further comprising applying a heat treatment following depositing at least one of the first and second layers. 
     
     
       27. The method of  claim 19 , further comprising applying a heat treatment after depositing both the first and the second layers. 
     
     
       28. The method of  claim 19 , wherein the alloy comprises a predominately γ-Ni+γ′-Ni 3 Al phase constitution. 
     
     
       29. The method of  claim 1 , further comprising:
 forming an alloy comprising the Pt-group metal, Si, and the reactive element; and 
 grinding the alloy into the powder comprising the mixture of the Pt group metal, Si, and the reactive element. 
 
     
     
       30. The method of  claim 1 , wherein the powder comprising the mixture of the Pt group metal, Si, and the reactive element comprises a substantially homogeneous mixture of the Pt group metal, Si, and the reactive element.